WordPress login bug. Need an emergency solution

This is definitely not related to a “missing” .htaccess file. WordPress will create an .htaccess file if needed (for permalinks) and re-create a deleted file if needed.

If you have deleted all previous data as you state and installed WordPress several times, you likely have a very messy DB and/or file situation going on.

Why not simply create a new DB, clear all the files out and start from scratch? 5 minutes or less and you have a fresh clean WP site ready to work with.